DARREN Criss had to get into the head of a spree killer for his new TV role.

The actor and singer, best known for his role as openly gay drama student Blaine on the TV series Glee, stars in the new instalment of Ryan Murphy's true crime anthology series American Crime Story.

Following on from the successful first season The People vs OJ Simpson, this new nine-part stand-alone season explores the killing spree of Andrew Cunanan which included the shooting of Italian fashion designer Gianni Versace on the steps of his Miami mansion.

"We get caught up in the really scary things, but we have more in common with the worst people we can think of than we care to admit," Criss says.

"We all have access to the same emotions and actions. There's a cocktail of variables for why we don't go down certain paths. I by no means in finding all my similarities forgive or exonerate anything Andrew did. But I know what it's like to have pain and hurt and longing. Most of that stuff doesn't stem from these scary moments but from very simple, relate-able things.

Darren Criss as Andrew Cunanan in a scene from American Crime Story: The Assassination of Gianni Versace.Supplied

"He was a bit of a showman. As an actor I can understand that - the desire to stand out, be ambitious, to leave a good impression. I'm also attracted to big ideas; I love flourish and embellishments.

"It becomes very easy to see how they get twisted and turned around. The point of attack (as an actor) is finding the best parts of somebody."

Cunanan killed four other men, including Chicago business tycoon Lee Miglin, before he shot Versace. The series, which is based on Maureen Orth's book Vulgar Favors, delves into those events which lead to his most infamous murder and subsequent suicide.

"The huge difference between the OJ story and this story is that most people don't know most of the story," Criss says. "I knew Gianni was tragically murdered on the steps of his home and I vaguely remember it was by a half-Filipino guy, but that happens in the first eight minutes of the series. There's a whole lot more to talk about."

Edgar Ramirez stars as Gianni Versace in the TV series The Assassination of Gianni Versace: American Crime Story.Supplied

Unlike his other dramatic roles, there was an added layer of responsibility for Criss in bringing a real-life tragedy to the screen.

"He was a real person who took very real people's lives and wrought havoc on peoples lives who are still alive today," he says.

"It's fun to play baddies when they're James Bond villains and you can play with the fantastical element, but when you're inhabiting someone real it's a different kind of invigoration. There's a great deal of responsibility of making sure to tell the story right and hit the emotional beats right to not only honour those taken away but somehow allow an audience to wrap their brains around how something like this can happen."

The drama also stars Edgar Ramirez as Gianni Versace, Ricky Martin as his partner Antonio D'Amico and Penelope Cruz as Donatella Versace. Murphy directs five of the episodes and is an executive producer.

Penelope Cruz in a scene from the TV series The Assassination of Gianni Versace: American Crime Story. Jeff Daly

"He was my boss on Glee but we had never worked together in the typical actor director relationship," he says.

"We talked about doing the Versace story before they made the OJ series. By the time it came out, if I wasn't already extremely excited about shooting this series then I was more excited after I saw how well he was working with true crime stories."

The Assassination of Gianni Versace: American Crime Story premieres tonight at 8.30pm on Showcase.